CN111735531A - Miniaturized MEMS capacitive composite co-vibration vector hydrophone - Google Patents
Miniaturized MEMS capacitive composite co-vibration vector hydrophone Download PDFInfo
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- CN111735531A CN111735531A CN202010692654.0A CN202010692654A CN111735531A CN 111735531 A CN111735531 A CN 111735531A CN 202010692654 A CN202010692654 A CN 202010692654A CN 111735531 A CN111735531 A CN 111735531A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
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Abstract
The invention discloses a miniaturized MEMS capacitive composite co-vibration vector hydrophone, which belongs to the technical field of underwater acoustic signal detection and comprises an MEMS capacitive accelerometer, a fixed core, a vertical suspension rod, a piezoelectric ceramic ring, an acoustically transparent sealed shell and a conical spiral spring; the MEMS capacitive acceleration sensor is orthogonally arranged in the fixed core; the vertical suspension rod penetrates through the whole fixed core; the piezoelectric ceramic ring is sleeved outside the fixed core; the sound-transmitting sealing shell covers the outer part of the piezoelectric ceramic ring through an encapsulating process. The conical spiral spring is connected with the vertical suspension rod to suspend the hydrophone on the fixed support for use. The hydrophone has the advantages of reduced volume, capability of detecting the sound pressure signal and the vibration velocity signal at the same position under water, improved signal detection accuracy, simple structure, good consistency and high reliability.
Description
Technical Field
The invention relates to the technical field of underwater acoustic signal detection, in particular to a miniaturized MEMS capacitive composite co-vibration vector hydrophone.
Background
The traditional scalar hydrophone, also called as a sound pressure hydrophone, is generally made of materials such as piezoelectric ceramics, has various shapes and sizes, is mainly used as a standard hydrophone, but can only measure scalar parameters in a sound field.
The inner core sensing element of the traditional co-vibrating vector hydrophone is a vibration sensor. Most of vibration sensors used in processing of domestic and foreign hydrophones are acceleration or speed sensors based on the piezoelectric principle. The traditional piezoelectric vector hydrophone is large in size, heavy in weight, complex in processing circuit at the rear end, limited by the traditional processing technology, poor in consistency, not easy to carry on multiple platforms and incapable of meeting the development requirement of the existing miniaturization and multiple platforms of underwater sound detection.
With the development of the micro-electro-mechanical system technology, the MEMS hydrophone combining the semiconductor device based on the MEMS technology and the traditional underwater acoustic field has the advantages of low noise, high sensitivity, good consistency and the like, can be highly integrated with a rear end ASIC circuit, greatly reduces the volume and weight of the hydrophone, reduces the influence on an original radiation sound field, and enables a detection result to be more accurate. The MEMS co-vibration vector hydrophone has three types of piezoresistive type, piezoelectric type and capacitive type. Piezoresistive and piezoelectric hydrophones are generally low in sensitivity, high in thermal noise and susceptible to temperature. The MEMS capacitive hydrophone has the advantages of high detection precision, high sensitivity and high stability, and can effectively widen the frequency bandwidth by matching with a closed-loop feedback circuit.
The patent with publication number CN1776390A discloses a "capacitive co-vibration vector hydrophone and a process thereof", wherein the vector hydrophone adopts a silicon micro-acceleration sensor as a sensitive element, but does not have scalar sound pressure detection capability; in patent publication No. CN208795359U, a "two-dimensional co-vibration vector hydrophone" is disclosed, and although this structure can realize composite information detection of sound pressure and vibration velocity, the following problems exist: 1) the vibration velocity sensing element and the sound pressure sensing element are vertically arranged, so that the size is large. 2) The vibration velocity sensing element and the sound pressure sensing element are not concentric, and sound field information cannot be accurately acquired. 3) The suspension structure is relatively complex and requires eight springs for support.
Disclosure of Invention
In view of this, the present invention provides a miniaturized MEMS capacitive composite co-vibrating vector hydrophone. The hydrophone can detect the sound pressure signal and the vibration velocity signal at the same position underwater, not only improves the accuracy of signal detection, but also has simple structure, good consistency and high reliability, and can meet the requirement of underwater low-frequency detection.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a miniaturized MEMS capacitive composite co-vibration vector hydrophone comprises a hydrophone main body and a suspension, wherein the hydrophone main body comprises a piezoelectric ceramic ring and a sound-transmitting sealed shell, wherein the outer surface of the piezoelectric ceramic ring covers and fills the piezoelectric ceramic ring; the piezoelectric ceramic ring is connected with the outside through a cable; the hydrophone body further comprises a fixed core and at least two MEMS capacitive accelerometers; the top and the bottom of the piezoelectric ceramic ring are covered with foam cover plates, the fixed core is positioned in the piezoelectric ceramic ring, the MEMS capacitive accelerometers are vertically arranged on the side wall of the fixed core, the adjacent MEMS capacitive accelerometers are mutually vertical, and the centers of the two MEMS capacitive accelerometers are positioned at the same height; the MEMS capacitive accelerometer is connected to the outside by a cable that penetrates the foam cover and the acoustically transparent sealed housing.
Furthermore, the hydrophone body also comprises a vertical suspension rod, the vertical suspension rod penetrates through the sound-transmitting sealed shell, the foam cover plate and the fixing core, and two ends of the vertical suspension rod are exposed out of the sound-transmitting sealed shell; the end parts of the vertical suspension rods are provided with through holes, and the through holes at the two ends are in an orthogonal relation.
Furthermore, the fixed core is a cylinder, and the vertical suspension rod penetrates through the center line of the cylinder; the MEMS capacitive accelerometer is embedded on the side wall of the cylinder.
Furthermore, the central line of the piezoelectric ceramic ring is superposed with the central line of the fixed core.
Furthermore, the number of the MEMS capacitive accelerometers is four, and the MEMS capacitive accelerometers arranged at intervals are in mirror symmetry.
Further, the suspension includes two conical coil springs; the conical heads of the two conical spiral springs are respectively connected with the upper through hole and the lower through hole of the vertical suspension rod.
Further, the material of the sound-transmitting sealing shell is polyurethane or butyl rubber.
Further, the hydrophone body is positioned at the geometric center of the suspension.
Further, the center of gravity of the body including the suspension coincides with the geometric center thereof.
Further, the vertical suspension rod and the conical spiral spring are made of stainless steel, titanium alloy or nylon materials.
The invention adopts the technical scheme to produce the beneficial effects that:
1. according to the invention, the MEMS capacitive accelerometer is arranged in the piezoelectric ceramic ring, so that the size and the volume of the hydrophone are reduced, scalar signals and vector signals at the same position under water can be measured simultaneously, and the completeness and the accuracy of sound field information acquisition are ensured.
2. According to the invention, the MEMS capacitive accelerometer is used as a vibration velocity pickup unit, so that signals can be amplified at the source end, and the attenuation caused by long-distance transmission of weak signals is avoided.
3. The invention effectively reduces the suspension size of the hydrophone by the conical spiral spring device vertically suspended from top to bottom, has simple structure and can avoid the interference of the horizontal suspension device on a horizontal sound field.
Drawings
FIG. 1 is an exploded view of a structure according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of a body of an embodiment of the present invention;
FIG. 3 is a schematic diagram of a conical coil spring suspended hydrophone in accordance with an embodiment of the present invention;
in the figure: 11. the MEMS capacitive accelerometer comprises a fixed core, 12 and 13, an MEMS capacitive accelerometer, 14, a horizontal bolt, 15, a vertical suspension rod, 16, a piezoelectric ceramic ring, 17, an upper foam cover plate, 18, a lower foam cover plate, 19, a vertical bolt, 32, a through hole, 33, an upper conical spiral spring, 34 and a lower conical spiral spring.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments.
The theoretical basis for scalar signal detection is: when the piezoelectric ceramic ring acts on a sound field, the piezoelectric ceramic ring can receive the excitation of an acoustic signal from an aqueous medium, force the piezoelectric material to generate forced vibration and deform, and induce electric charges, so that the vibration signal is converted into an electric signal to be output, and the scalar detection of the acoustic signal is realized.
The theoretical basis of vector signal detection is as follows: if the geometric circle of the rigid acoustic main body is smaller than the wavelength, the rigid acoustic main body freely vibrates under the action of underwater sound waves, and the vibration velocity amplitude V of the rigid acoustic main body and the vibration velocity amplitude V of water particles at the geometric center of gravity of the rigid acoustic main body in a sound field0There are the following relationships between:
wherein: rho0-the density of the aqueous medium,
average density of rigid cylinders.
According to the formula, when the average density of the rigid column is
Equal to the density of the aqueous medium rho0The vibration velocity amplitude V of the rigid acoustic cylinder and the vibration velocity amplitude V of the rigid acoustic cylinder0And similarly, the vibration velocity is picked up by the MEMS capacitive acceleration sensor in the rigid column, and the vibration signal is converted into an electric signal to be output, so that the vibration velocity of the water particle at the geometric gravity center position of the hydrophone in the sound field can be obtained.
In summary, combining the detection principle of scalar signals and vector signals, it can be known that the recorded sound field information is accurate only when the sound pressure signal and the vibration velocity signal are acquired at the same position of the aqueous medium, and therefore, the closer the piezoelectric ceramic ring and the vibration sensor are, the better the recorded sound field information is.
A miniaturized MEMS capacitive composite co-vibration vector hydrophone comprises a main body and a suspension, wherein the main body comprises a piezoelectric ceramic ring and an acoustic transmission sealed shell, wherein the outer surface of the piezoelectric ceramic ring covers and is filled; the piezoelectric ceramic ring is connected with the outside through a cable; the main body further comprises a fixed core, a foam cover plate and at least two MEMS capacitive accelerometers; the top and the bottom of the piezoelectric ceramic ring are covered with foam cover plates, the fixed core is positioned in the piezoelectric ceramic ring, the MEMS capacitive accelerometers are vertically arranged on the side wall of the fixed core, and the adjacent MEMS capacitive accelerometers are mutually vertical and positioned at the same height; the MEMS capacitive accelerometer is connected to the outside by a cable that penetrates the foam cover and the acoustically transparent sealed housing.
Furthermore, the main body also comprises a vertical suspension rod, the vertical suspension rod penetrates through the sound-transmitting sealed shell, the foam cover plate and the fixing core, and two ends of the vertical suspension rod are exposed out of the sound-transmitting sealed shell; the ends of the vertical suspension rods are provided with through holes 32, and the through holes at the two ends are in an orthogonal relation.
Further, the fixed core is a cylinder, and the vertical suspension rod penetrates through the center line of the cylinder; the MEMS capacitive accelerometer is embedded in the side wall of the cylinder.
Furthermore, the central line of the piezoelectric ceramic ring is superposed with the central line of the fixed core.
Furthermore, the number of the MEMS capacitive accelerometers is four, and the MEMS capacitive accelerometers arranged at intervals are in mirror symmetry.
Further, the suspension includes two conical coil springs; the conical heads of the two conical spiral springs are respectively connected with the upper through hole and the lower through hole of the vertical suspension rod.
Further, the material of the sound-transmitting sealing shell is polyurethane or butyl rubber.
Further, the body is positioned at the geometric center of the suspension.
Further, the center of gravity of the body including the suspension coincides with the geometric center thereof.
Further, the vertical suspension rod and the conical spiral spring are made of stainless steel, titanium alloy or nylon materials.
The following is a more specific example:
as shown in fig. 1, the present embodiment includes a fixed core 11, a MEMS capacitive accelerometer 12, a MEMS capacitive accelerometer 13, a vertical suspension rod 15, a piezo ceramic ring 16, an upper foam cover plate 17, and a lower foam cover plate 18.
The two MEMS accelerometers are orthogonally fixed on the fixed core 11 through a horizontal screw 14 and are kept vertical to the horizontal plane; the vertical suspension rod 15 vertically penetrates through the central hole of the fixed core 11 and is fixed through screws; the piezoelectric ceramic ring is sleeved outside the assembled fixed core 11, and the piezoelectric ceramic ring and the assembled fixed core 11 are coaxial; the upper foam cover plate 17 and the lower foam cover plate 18 are respectively arranged at the upper opening and the lower opening of the piezoelectric ceramic ring and are fixed through vertical screws 19.
The exterior of the assembled structure needs to be encapsulated to form a sealed shell, and the cross-sectional view of the encapsulated hydrophone body is shown in fig. 2, and comprises the assembled structure according to fig. 1, an acoustically transparent sealed shell and a vertical suspension rod 15. The sound-transmitting sealing shell is made of sound-transmitting polyurethane and is formed by integrally encapsulating, heating and curing through a special mold. On one hand, the sound-transmitting sealing shell ensures that all parts of the composite co-vibration vector sensor can be sealed, insulated and isolated from water, and can normally work; on the other hand, the sound pressure signal and the vibration signal in the water can be transmitted to the annular piezoelectric ceramic ring and the MEMS capacitive accelerometer respectively without attenuation.
The overall density of the hydrophone body after encapsulation is close to 1g/cm3The buoyancy state can be maintained in water.
The hydrophone body after encapsulation is suspended on the fixed support through the coil springs, as shown in fig. 3, and includes the hydrophone body after encapsulation in fig. 2, a vertical suspension rod, an upper conical coil spring 33, and a lower conical coil spring 34. The upper conical spiral spring and the lower conical spiral spring are connected with the upper through hole 32 and the lower through hole 32 of the vertical suspension structure of the hydrophone through hooks at the bottom, and are suspended on the fixed support for use after being tensioned.
The upper through hole and the lower through hole of the vertical suspension rod are orthogonally arranged and are connected with the conical spiral spring hook, so that the hydrophone can be prevented from rotating in the using process.
The elastic coefficient k of the upper conical spiral spring and the lower conical spiral spring enables the hydrophone to be positioned at the gravity center and the geometric center of the fixed support in a suspended state in water, and can freely vibrate in a horizontal plane along with sound waves in the water.
Vector hydrophone performance evaluation:
step 1) directivity test.
And (4) carrying out directivity test on the vector hydrophone according to the national vector hydrophone calibration standard. The test is carried out in a standing wave tube, the test frequency range is 20 Hz-2 kHz, the directivity is in a shape of '8', the depth of a concave point is more than or equal to 30dB, and the directivity is good.
And 2) testing the sensitivity.
And (4) carrying out sensitivity test on the vector hydrophone according to the national vector hydrophone calibration standard. The test is carried out in a standing wave tube, the test frequency range is 20Hz to 2kHz, the sensitivity curve linearly increases according to +6dB per octave, and the sensitivity at 1kHz is more than or equal to-163 dB.
While the principles of the invention have been described in detail in connection with the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing embodiments are merely illustrative of exemplary implementations of the invention and are not limiting of the scope of the invention. The details of the embodiments are not to be interpreted as limiting the scope of the invention, and any obvious changes, such as equivalent alterations, simple substitutions and the like, based on the technical solution of the invention, can be interpreted without departing from the spirit and scope of the invention.
Claims (10)
1. A miniaturized MEMS capacitive composite co-vibration vector hydrophone comprises a hydrophone body and a suspension, wherein the hydrophone body comprises a piezoelectric ceramic ring (16) and an acoustic transmission sealed shell, and the outer surface of the piezoelectric ceramic ring covers and fills the acoustic transmission sealed shell; the piezoelectric ceramic ring is connected with the outside through a cable; the hydrophone is characterized in that the hydrophone body further comprises a fixed core (11) and at least two MEMS capacitive accelerometers (12); the top and the bottom of the piezoelectric ceramic ring are covered with foam cover plates, the fixed core is positioned in the piezoelectric ceramic ring, the MEMS capacitive accelerometers are vertically arranged on the side wall of the fixed core, the adjacent MEMS capacitive accelerometers are mutually vertical, and the centers of the two MEMS capacitive accelerometers are positioned at the same height; the MEMS capacitive accelerometer is connected to the outside by a cable that penetrates the foam cover and the acoustically transparent sealed housing.
2. The miniaturized MEMS capacitive composite co-vibrating vector hydrophone of claim 1, wherein the hydrophone body further comprises a vertical suspension rod (15), the vertical suspension rod penetrates through the acoustically transparent sealed shell, the foam cover plate and the fixed core, and two ends of the vertical suspension rod are exposed out of the acoustically transparent sealed shell; the end parts of the vertical suspension rods are provided with through holes, and the through holes (32) at the two ends are in an orthogonal relation.
3. The miniaturized MEMS capacitive composite co-vibrating vector hydrophone of claim 1, wherein the fixed core is a cylinder, and the vertical suspension rod passes through a center line of the cylinder; the MEMS capacitive accelerometer is embedded on the side wall of the cylinder.
4. A miniaturized MEMS capacitive composite co-vibrating vector hydrophone according to claims 1 or 3 wherein the center line of the piezo-ceramic ring coincides with the center line of the stationary core.
5. The miniaturized MEMS capacitive composite co-vibrating vector hydrophone of claim 1, wherein the number of MEMS capacitive accelerometers is four, and the spaced MEMS capacitive accelerometers are mirror images.
6. The miniaturized MEMS capacitive composite co-vibrating vector hydrophone of claim 2, wherein the suspension comprises two conical coil springs; the conical heads of the two conical spiral springs are respectively connected with the upper through hole and the lower through hole of the vertical suspension rod.
7. The miniaturized MEMS capacitive composite co-vibrating vector hydrophone of claim 1, wherein the acoustically transparent hermetic enclosure is made of polyurethane or butyl rubber.
8. The miniaturized MEMS capacitive composite co-vibrating vector hydrophone of claim 6, wherein the hydrophone body is centered geometrically on the suspension.
9. A miniaturized MEMS capacitive composite co-vibrating vector hydrophone according to any of claims 1-6, wherein the center of gravity of the body including the suspension coincides with its geometrical center.
10. The miniaturized MEMS capacitive composite co-vibration vector hydrophone according to any one of claims 1-6, wherein the vertical suspension rods and the conical coil springs are made of stainless steel, titanium alloy or nylon.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010692654.0A CN111735531A (en) | 2020-07-17 | 2020-07-17 | Miniaturized MEMS capacitive composite co-vibration vector hydrophone |
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| CN202010692654.0A CN111735531A (en) | 2020-07-17 | 2020-07-17 | Miniaturized MEMS capacitive composite co-vibration vector hydrophone |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113075726A (en) * | 2021-05-10 | 2021-07-06 | 联合微电子中心有限责任公司 | Hydrophone and method for manufacturing same |
| CN113639852A (en) * | 2021-07-20 | 2021-11-12 | 哈尔滨工程大学 | Torsional non-inertial vector hydrophone |
-
2020
- 2020-07-17 CN CN202010692654.0A patent/CN111735531A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113075726A (en) * | 2021-05-10 | 2021-07-06 | 联合微电子中心有限责任公司 | Hydrophone and method for manufacturing same |
| CN113639852A (en) * | 2021-07-20 | 2021-11-12 | 哈尔滨工程大学 | Torsional non-inertial vector hydrophone |
| CN113639852B (en) * | 2021-07-20 | 2024-01-02 | 哈尔滨工程大学 | Torsion type non-inertial vector hydrophone |
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